Strap wrenches are known in which a chain or flexible strap has one end fixed and another end loose for frictionally engaging an annular body for turning by a levering element, such as the socket of a socket wrench or a socket screwdriver. Known constructions have several disadvantages, particularly in that the strap for mounting about an annular body such as a cylindrical oil filter is not adjustable in circumference.
Strap wrenches which utilize a band of steel having a socket receiving member are well known. However, when a metallic strap is utilized, this does not provide for adjustment of size and does not provide tight gripping on the object. Such a construction is shown in U.S. Pat. No. 4,114,481.
Other types of adjustable strap wrenches have been disclosed in the past. For example, U.S. Pat. No. 4,037,495 discloses a strap wrench which is adjusted in circumference through hook and loop connections.
Flexible strap wrenches adapted to fit around a cylindrical object such as an oil filter, are disclosed in U.S. Pat. Nos. 4,249,296, 2,995,965, and 4,506,568. The strap wrenches disclosed in these patents rely solely on frictional engagement of the strap about the object to be turned. In U.S. Pat. No. 4,506,568, a specially designed levering body is utilized to receive two ends of a strap and supposedly a two-part holder structure prevents any change in the circumference of the strap once the circumference is set. However, the device shown in U.S. Pat. No. 4,506,568, as well as that shown in U.S. Pat. No. 2,995,965, are subject to slippage of the strap in the wrenching member.
The present invention provides a simple and economical strap wrench which may be infinitely adjusted and fixed as to circumference, and which provides increased frictional engagement of the strap wrench with the part to be acted upon and does not disturb the fixed circumference. The construction of the strap wrench is economical and simple and permits the turning of an object of any size in restricted spaces.